SQLite is a database, and you need to define indexes for columns that you will be selecting. (You may want to read a good database book for examples of when, and when NOT to use an index... for that matter, when you want to use a database and when to use a delimited text file...) Adding an index improves performace, at least at select time. Not tested for replace time, but I leave that as an exercise to the user...
Example code: